1. Field of the Invention
The present invention is directed towards the field of communications network management. More particularly, the present invention relates to processing management frames transmitted between a physical layer device and a station management entity.
2. Description of the Related Art
Communications networks provide for the transfer of information between pieces of data terminal equipment, such as personal computers. One standard for a communications network is the Institute of Electrical and Electronics Engineers ("IEEE") 802.3u standard, which is set forth in IEEE Standards for Local and Metropolitan Area Networks: Supplement to Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications, Media Access Control (MAC) Parameters, Physical Layer, Medium Attachment Units, and Repeater for 100 Mb/s Operation, Type 100BASE-T (Clauses 21-30), The Institute of Electrical and Electronics Engineers, Inc., 345 East 47th Street, New York, N.Y. 10017-2394, 1995, which is hereby incorporated by reference.
A communications network may be required to transfer a great deal of information. Under heavy utilization conditions, a communications network's performance may be degraded, or the communications network may cease operating. By continually monitoring the operation of a communications network, it may be possible for a network management entity to detect the potential for such degradations and failures. The network management entity can then take actions that will assist in avoiding any degradations or failures. In order to provide a network management entity with the information necessary to manage a communications network, different components in the communications network may record network status information and make it available to the network management entity.
FIG. 1 illustrates a repeater set 100, as specified in the IEEE 802.3u standard, including a station management entity 106, which is also identified in the IEEE 802.3u standard. The repeater set 100 provides for the transfer of information between multiple medium connections in an IEEE 802.3u communications network.
The repeater set 100 includes a repeater unit 101 and a plurality of transceivers 102. Each transceiver 102 may be coupled to a respective medium 103 that carries information through the network. Each transceiver 102 is coupled to a respective medium 103 via a medium dependent interface ("MDI") 104 that is specified in the IEEE 802.3u standard. Each medium 103 is also attached to either data terminal equipment (not shown), another repeater set (not shown), or another piece of networking equipment (not shown), such as a bridge or a router. Each transceiver 102 receives and transmits data over its respective MDI 104.
Each transceiver 102 is coupled to the repeater unit 101 through a medium independent interface ("MII") as specified in the IEEE 802.3u standard. The MII includes a set of physical signaling sublayer signals ("PLS") 105 for connecting the transceiver to the repeater unit 101. The PLS signals 105 provide for transmit data to be passed from the repeater unit 101 to the transceiver 102, receive data to be passed from the transceiver 102 to the repeater unit 101, and for carrier and collision signals to be passed to the repeater unit 101 by the transceiver 102.
The MII also includes a management bus ("MB") 107, which is employed to couple a station management entity 106 to a set of transceivers 102. Each transceiver 102 may internally maintain a set of network status information, including information relating to the operation of the link between the transceiver 102 and its respective medium 103. Each transceiver 102 may also include a control register and other various registers that are programmable and readable by the station management entity 106.
The station management entity 106 retrieves such network status information and accesses transceiver registers via the management bus 107. The station management entity 106 thereby provides a means for a network administrator to gather network status information and program the operation of transceivers 102 to avoid future network degradations and failures.
The station management entity 106 communicates with each transceiver 102 coupled to the management bus 107 through the use of management frames. However, if a management frame deviates from the frame template specified in the IEEE 802.3u standard, a transceiver 102 may receive erroneous instructions, thereby causing the transceiver 102 to perform an erroneous operation. For example, an improper management frame may cause two transceivers 102 to erroneously believe that they are designated to drive the shared management bus 107. As a result, there may be contention on the management bus 107 and the network administrator may either receive erroneous data or have an instruction executed improperly.